If you're in the US, then you could get that information from your local national weather service office. You could also get data from the National Climate Data Center (NCDC) that would allow you to figure that out, but it might be more trouble to do that than it is worth. You can find out which office is responsible for your area by checking this list:
http://www.nws.noaa.gov/organization.php
Each office should have a page Climate/Local that may contain that information--the data they put on the page varies from site-to-site. If you can't find it on their web page, there should be another link on the website "Contact Info". Send them an email or call them directly and ask nicely for the information, and they should get it to you. It may take a few days, especially if it's a busy weather time for them. But don't be shy about asking--your tax dollars are paying their salaries!
I think similar information is available in other countries. In Canada you would contact Environment Canada, in the UK contact the Met Office, and in Australia contact the Bureau of Meteorology.
EDIT: Since you're in Salt Lake City, here is a plot of the data you want that I found on the NWS Salt Lake City site:
http://www.wrcc.dri.edu/cgi-bin/cliMAIN.…
Unfortunately I can only find it as a graph and not in tabular format. The source is the Western Regional Climate Center (WRCC) and Desert Research Institute (DRI), but I could not find the data that went into the graph on those sites. Call or email the NWS Salt Lake City and ask for the data. (If you're really shy I'll do it for you, lol)